In automotive vehicles, diagnostic modules are provided for self-diagnosing systems to activate devices for warning vehicle operators if a problem or fault occurs in the system which either will or will potentially effect the system's performance. No system currently exists for emitting a warning signal if a diagnostic module is disconnected due to either a loose wiring connector or an unconnected wiring connector.
Current vehicle systems presently use a bulb check which automatically turns on a warning light or signal for a given time when the ignition key is turned on or when the vehicle is started for a prescribed time. When the vehicle's operator does not see the light or another indicator during the key-on test, the operator knows that the system needs servicing. It is a disadvantage of this system that the driver must watch for the light during the bulb check interval. It is necessary to have this "key-on" test because present diagnostic modules are not configured to turn on warning lamps, buzzers or other devices when they are physically disconnected from the system.
Of specific interest with respect to this problem are connectors employed in air bag systems where the connectors can, for one reason or another, become disconnected. In air bag systems, an air bag is folded and packed into a housing mounted on a steering wheel for protecting a driver or in the dash board in front of the passenger. Air bags utilize an inflater operated by a squib heating element which is energized by an air bag operating circuit including a power source, deacceleration responsive sensors and a connector for electrically connecting the components of the system to one another. Upon the occurrence of a crash, current from the power source is applied to squib to the heat chemicals in the inflater which expands to inflate the air bar with resultant gases. If the air bag system diagnostic module connector is disconnected, the air bag will not operate in an emergency. Accordingly, it is important that the integrity of these electrical connections be maintained.
In U.S. Pat. No. 5,034,727, issued Jul. 23, 1991, to Muraoka, the problem of disconnected electrical connectors is addressed. However, in Muraoka, the arrangement is only useful to check the integrity of electrical connections on the assembly line. Muraoka is not concerned with notifying the vehicle Operator that air bag electrical connectors are disconnected so that the vehicle operator can take steps to correct the problem.
In view of the aforementioned situation, there is a need for an indicating means to inform operators, such as vehicle operators, that an electrical connection has been compromised.